At the moment the mesothelioma treatment that does the best job of lengthening patients’ lives is a combination of Platinol (cisplatin) and either Alimta (pemetrexed) or Tomudex (raltitrexed). But survival rates are still low, with only half of patients living longer than 12 months after treatment.

Adding biological agents that target cancer-linked proteins to standard chemotherapy has had little impact on mesothelioma, highlighting the urgent need for new drugs.

There are three subtypes of mesothelioma. Epithelioid accounts for about half of cases, sarcomatoid 16 percent, and biphasic — a mixture of epitheliod and sarcomatoid — 34 percent.

Scientists say sarcomatoid mesotheliom tumors are aggressive. They are more likely to spread to other parts of the body and to resist treatment. And they have poorer outcomes.

Ptac2S is a platinum-based therapy that is 12 times more effective than Platinol in reducing the growth of epithelioid mesothelioma in mice.

Researchers wanted to see if it would also work against sarcomatoid mesothelioma. They first used Ptac2S against lab-grown cells taken from a sarcomatoid mesothelioma tumor. Then they used it against sarcomatoid mesothelioma tumors in mice.

Ptac2S halved the tumor cells’ growth rate, compared with Platinol. It also reduced the mice’s tumor mass by 53 percent, in contrast with Plationol’s 12 percent.

“Ptac2S is effective in pleural mesothelioma,” the researchers wrote. Its use in medical practice could “improve the response to chemotherapy of resistant tumors.”

“Results confirm that Ptac2S is a promising therapeutic agent for malignant mesothelioma, giving a substantial starting point for its further validation,” they concluded.